Bevel-gear-cutting machine.



N0. 668,772. Patented Feb. 26, |90l.

T. COVENTRY. BEVEL GEAR CUTTING MACHINE.

` (Application led Feb. 8, 1900.) :(No Model.) 5 s haets-Sheet l.

no. ssa,772.

, Patented Fab. 26, |90I. T. CDVENTRY. BEVEL GEAR {IUTTING MACHINE.

(Appliation filed Fe'n. B. 1900.)

5 Sheets-Sheet 2.

(No Model.)

No. 668,772. Pafentedreb. 2s, Ism. 'r. covenrnv. BEVEL GEAR CUTTINGMACHINE.

ashun-snee; 3.

(Application led Feb. 8, 1900.)

(No Model.)

IIL

.wrracnms news co, PHoToLlTHo.. WASHINGTON. o. s:4

No. 668,772. Patented Feb. 26, I90I. T. CUVENTBY.

BEVEL GEARA CUTTING MACHINE.

(A'ppumiqq med Feb. s, 1900.) Il o l o d e l 5`Sheeis-Sheet 4.

THE Ncnms PETERS co, PHu'mLlmo., wAsNvNm-ou. n c.

No. 668,772.I

- y Patented Feb. 26, |90I. T. COVENTRY.

BEVEL GEAR CUTTING MACHINE.

(Application med Feb. e, woo.l

5 Sheets-Sheet 5.

(no Modem Mwr mw is a detail of a tool-holder.

UNrrr; STATES PATENT OFFICE.

THEODORE COVENTRY, OE MANCHESTER, ENGLAND, ASSIGNOR TO SMITH ANDCOVENTRY, LIMITED, OF SALFORD, MANCHESTER, ENGLAND.

BEVEL-GEAR-CUTTING MACHINE.

SPECIFICATION forming part of Letters Patent No. 668,77 2, datedFebruary 26, 1901.

Application-ined February 8, 1900Vl Serial No. 4,523. (No model.)

i'o tl/t whom t may concern:

Be it known that I, THEODORE COVENTRY, a subject of the Queen of GreatBritain, residing at Salford, Manchester, in the county of Lancaster, England, have invented certain new and useful Improvements in Bevel-Gear-Cutting Machines; and I do hereby declare the following to be a full,clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame, reference being had to the accompanying drawings, and tocharacters of reference marked thereon, which form a part of thisspecification.

My invention relates to machines for cutting miter and other bevel gearsin which there is one of a pair of reciprocating cutting-tools travelingin radial lines from a central support and taking cuts along the breadthof the tooth as the wheel-blank is fed up to the tools, these same cutsbeing taken on each tooth successively, in order to do which thewheel-blank is rotated after each cut, or each tooth may be finishedseparately; and the invention has for its object improved meansforactuating the cutters, for feeding the blank thereto, and foractuating the machine, as will be fully described in thepfollowingspeci-V fication and particularly pointed out in the claims.

Referring to the drawings, in which like parts are similarly designated,Figure l is a perspective view of my improved machine, part of the standor frame .being broken away. Fig. 2 is a perspective view showing theopposile side of the Vcarriage to that shown in Fig. l, with theformer-arms removed. Eig. 3 is a plan view, partly in section. Fig. 4 isa side elevation, partly in section, of the front part of the carriage.Fig. 5 is a section through the former-arms on the line A A, Fig. 3.Fig. 6 is asection through the axis of t-he driving-pulley. Fig. 7 is asection through the former-arms on line B B, Fig. 3.

Eig. 9 is a diagram illustrating the adj ustmeut-scales.

Bevel-gears are cut from a conical blank or rather one having the formof a truncated right cone, and the teeth that are cut thereon have endsthat are trapezoidal in form,

Fig. s'

it is necessary to guide the cutting-tools, so that the distance betweenthem becomes narrower as they proceed on their cut, it of course beingunderstood that the tools travel from the base toward the apex of theblank, although they might be arranged to travel in the oppositedirection; but the former is preferred. Thus it is seen that the toolstravel Ain straight lines, and in order to make involute teeth 'thedistance apart of these tools must be varied, so that a .conical surfacewill be cut from the point to the root of the tooth, whose elements arestraight lines and Whose section is the involute shape desired.

The machine shown is entirely automatic, after being set to work, beingdriven from a single belt-pulley which operates the mechanism forreciprocating the tools, for turning the blank to be cut, and forfeeding the blank toward the tools.

In the drawings, in which I have shown my machine as provided with apair of cuttingtools adapted to cut from the base toward the apex of theconical blank, b is a stepped driving-pulley from which the entiremachine is operated. This pulley is mou nted on a sleeve b and thelatter on a stub-shaft b2, bolted to the frame of the machine. Thispulley b drivesapinion b", mounted on the same sleeve b, which piniondrives a gear-wheel b5, fast on the end of a shaft b, journaled in theframe, the front end of said shaft h6 carrying a disk 57, provided witheither a radial or a diametrical slot b1", in which a stud 58 isadjustable to form a crank whose length is variable. It is this studthat indirectly drives the tools, while their distance apart iscontrolled by other mechanism to be described. The stud bs is connectedto a reciprocating slide b by means of a rod b9.

The slide ha works in a pair of slideways bb, which togetherl form adovetailed groove in the frame, the upper one of which ways is providedwith a wear-plate be, adjustable by means of screws bf, to lake up thewear of the rubbing parts. The slide ba is connected by rods bc to eachof the tool-slides bd and reciprocates said slides in unison onslideways c2 on the former-arms c, said arms being the their pointsbeing elements of a cone. Hence l sired curve to the face and dank ofthe tooth,

, devices for spacing the tools to give the de- IOC as will hereinafterappear. These slideways c2 are dovetails on which slide the tool-carrierslides b, each of said slides being provided with a dovetail groove onits back, fitting the slideways c2 on the former-arms and provided withan adjustable Wear-plate. The front of each of these tool-carrier slidesbi has a longitudinal undercut slot bh, into which the tool-carriers Kare fastened to reciprocate with the slides that carry them. Thesetool-carriers K (shown in detail in Fig. S) comprise a body portion orbase le, which has a perforation in each end for bolts la', whose headstake into the undercut slots bl1 in the tool-carrier slides bd and whosenuts firmly clamp the tool-carrier in position on said slides. To saidbody portion or base 7c is hinged at one end the tool-holder proper bymeans of the pin 766, and in the base is also a cam 1:8, provided with alever 7c, operated by tappets at each end of the travel of the tools 7a4to cam out the tool-l1older and throw the cutting edge of the tool clearof the metal to be worked upon to prevent the tools from scraping duringtheir return.

The tool-carrier k2 has a projecting nose lag, which is acted on by acoil-spring kf, located between it and the base k to turn thetoolcarrier back into the cutting position after the cam is withdrawn.The front portion 7c3 issecured to the portion 7a2 by means of bolts c,passing through the vertical slots in said front portion, and on top ofthis part is secured a bracket k by means of screws kp, said bracketworking in a collar on an adjustable screw cq, whereby when looseningthe nuts h5 the vertical adjustment of the tools can readily beeifected. The tool itself is held in a dovetailed or undercut slot ki bymeans of a screw km and wedge kl.

Secured to and projectingr from each slideway c is a pair of bracketske, carrying a rod kd, from which project fingers or tappets kc,adjustable along the rod, that act on the lever 7c to operate the camles at each end of the travel of the tools to trip and to return thetool-carrier again to cutting position.

Theformer-arms c, on which travel the toolcarrier slides, have a commonfulcrum at one end on a stud c in the frame a, while their oppositeends are enlarged and contain arcuate slots c3, struck from the fulcrumc' as center, and each arm is provided with a scale c4, which isadjusted from a line on the index-arms c5, projecting from the frame.

In order to prevent the former-arms from twisting, a bolt cis secured toeach and passes through a slot c7 in the frame, said bolts beingdesigned to securely hold the formel'- arms while roughing out the work.In brder to further prevent the former-arms from twisting, especiallywhen these bolts are loosened during the finishing, I provide aprojection c8 on the edge of each former-arm, that takes under a guidehook or plate cw, secured to the frame by screws ci.

The former-arms are adjusted by means of the scales and indices to setthe tools, and when properly adjusted are clamped by the set-screws d8,which are rigid in parts dT, pivoted in slide-blocks d5, that havemotion in parallel channels d20. The slides d5 and parts (Z7 formconnect-ions between the ends of the former-arms and the parallel motionfor spreading said arms, which motion comprises the parallel channelsd20, connected by means of a common link or radial arm d, centrallypivoted at d to the frame, and a pair of links d3 of equal length, oneon either side of the link d and pivoted at one end to the frame at d*and at the other end to the respective chali-Y nels 6120. On the upperchannel d20 there is a graduated scale (Il, which can be set to an indexdk, held in an arm cl2, rising from the boss of the pivot d on theframe. It is evident that by varying the angle between the links d d3and the line of centers the distance between the channels can be varied,said channels always remaining parallel and resulting in a variation ofspread of the former-arms pivoted in them. Near the lower end of thelink d there is pivoted at (19a connectingrod d, adjustable by a bolt dbin a slotted graduated lever CZC. This lever is connected to abevel-gear (le, journaled in a bracket from the frame, and meshes with asimilar gear (Z5, journaled in a bracket a3 from the frame, and carriesa toothed sector d", which sector meshes with a rack formed on the endof an arcuate bar 10. This bar has bearing in and motion throughbrackets di from the frame a and is moved by and concentric with thecarriage that feeds the blankfw to the tools. The movement of the rod bythe carriage will rotate the sector d" and bevel-wheel d5, which willmove the bevel-wheel d gearing with it and draw the lever d down towardthe frame a, which in turn will rotate the two-armed lever or link (l onits pivot and move it toward vertical position to increase the distancebetween the parallel channels d20 and spread the former-arms c, pivotedtherein, producing the tinal result of spreading the toolsproportionately.

In front of the tool-carrying mechanism on the frame a is secured atable e3, approximately a quadrant, having a boss that fits a hole inthe frame, and on the edge of the table are formed worm teeth, and nearits edge is a circular scale ci, divided into degrecs, and near it anundercut slot eh, in which a stop j is adjustable by means of a boltj7.It is on this table e3 that the carriage is moved from thedriving-pulley by means of intermediate mecl1anism,which is arranged asfollows: On the spur-gear b5 I bolt a plate f, having in it a cam-groovej", in which travels a bowl on the upper end of a lever f2, pivoted atf3 on the back of the frame. The lower-slotted end of this lever f2 isconnected by a rod f4 and a crank-arm f5 to a rock-shaft f, supported inbearings in the framing, which shaft carries a rock-shaft f7, carrying abowl that engages a bobbin f8, loose on the ICO IIO

anis fg of the table. This arrangement causes a rocking motion to beimparted to the rockshaft f6 at the end of every revolution of thecam-groove, which vertically reciprocates the bobbin f8. The carriagecomprises a baseplate e, provided with a bearing fitting a tubular stude5, passing up through the table e3 and base-plate. This stud e5supports under the table a bracket 615, hereinafter referred to, and islocked in position by a washer and nut e6 on the upper end of thedescending stud fg, which forms the center around which the carriagemoves. On the carriage are formed undercut slideways e7, one of whichhas a wear-plate es, adjustable by screws e9. slides and is adjusted bya screw g', rotating in a boss on the carriage and having collars oneither side thereof to prevent endwise motion.

The outer end of the screw g is squared for a key, while the inner endcarries a thread and engagesa nnt held in a recess in the headstock tomove the latter radially.

In the head-stock is held a tubularA shaft g2, its inner end being conedto it into a complementary socket in the head-stock and locked inposition by the washer and locknuts g3. The inner end of this tubularshaft g2 is also coned internally to receive the coned shank of amandrel gw, which is tapped to receive the end of the long set-screw g8through the center of the tubular shaft g2. Various sizes of mandrelshaving the same size shank and fitting various wheel-bosses can be used,and these blanks are secured upon the end of the mandrel against acollar g, turned thereon (or loose collars to suit the various sizes ofwheel-bosses may be used) by means of a washer and nut g9 upon the end,which at this portion of the mandrel is threaded and has a reducedprojection g19 extending over the vertical axis of the carriage' andwhich enters a bearing in a standard or tail-stock Q20, adjustable alongan undercut slot 62, and rotates therein. This is to steady the endofthe mandrel Q7 against the pressure of the cutting-tools and preventthe work from giving under them. Rising from the outer end of thecarriage is a standard eg, bolted to the carriage and having a bore inalinement with the axis of lthe mandrel. In the bore of said standard isjournaled a sleeve g4, provided with a collar g5 at its outer end andhaving a featheror key gli',

sliding ina keyway Q12 in the tubular shaft g2, that has bearing in thissleeve, whereby the sleeve and shaft are caused to rotate togetherwithout hindering the longitudinal motion of the shaft and theadjustment of the head-stock in which this shaft g2 is secured. On theinner end of the sleeve g4 is fastened an eccentric and strap t', which,together with the collar g5, prevent displacement of the sleeve duringthe adjustment of the headstock g. The dividing-wheel h is securednextto the collar by a one or two armed screw- In these ways thehead-stock gl nut g, whose two halves are screwed together on the end ofthe sleeve g4 by two bolts Q71. Oscillating on a bearing on the standardback of the dividing-wheel is a two-armed lever h5, carrying on one endthe spring-controlled pawl hg for turning the dividing-wheel hand on itsopposite end a cam-face hf, the object of which is to cam out ofengagement from the dividing-wheel the spring-held retainingpawl ha,pivoted to the standard egA Secured to the top of the standard is abracket hm, which is clear of the movement of the arm h5 and carries athumb-screw and nut h1, whose head slides in a concentric slot h3 in apartial disk hi for locking the same in position, said partial diskbeing journaled on the collar g5 just behind the dividing-wheel h. Theobject of this disk,whose edge projects slightly beyond the teeth of thedividing-wheel, is to block ont from effective action any number ofteeth on the dividing-wheel, so that the pawl 71,9 will move the wheel ashorter or longer distance, so that a dividing wheel having any givennumber of teeth may be used to enable the machine to cut any gear whosenumber of teeth is a factor of the number of teeth of thedividing-Wheel. For instance, by using a wheel with one hundred andtwenty teeth the disk can be adjusted, so that the pawl hg will passover and move the dividing-wheel a distance of eight, six, five, four,three, two, one teeth ateach movement, thus cutting gears with fifteen,twenty, twenty-four, thirty, forty, sixty, or onehundred and twentyteeth, respectively. With pattern or dividing wheels having a differentnumber of teeth other gears can be cut.

Below the carriage depends a bracket em, which has journaled therein arock-shaft hw,

having an arm hx, connected to the lever h5 by means of the connectingrod h4, the opposite end of this shaft being supported in the bracket e,before referred to, at the pivot of the table, and as the table movesabout its center this bracket moves with it. From this end of therock-shaft hw is an arm h2, carrying a bowl that enters the bobbin f8.It is no'w clear that the power imparted to the'cam f and therock-shaft-f is transmitted through the bobbin fs to the secondrock-shaft hw on the carriage, the bobbin forming a joint between thesetwo rock-shafts, and a step-bystep motion is given to the dividing-wheelh at every revolution of the spur-wheel d5 and reciprocation of thetools. The feed of the carriage toward the cutters, which takes place atevery revolution of the dividing-wheel h and when every tooth hasreceived one cut, is actuated by the eccentric z', which is connected byits rod 2 to the rocker-arm 12 on one end of a rock-shaft 4, journaledin the side of the carriage and carrying on its forward end a yoke Gandpawl 8, said yoke straddling a spur-wheel 5, loose on the shaft 4. Thepawl 8 may be arranged to take one or more teeth by means of an adjust-able plate fa, similar to that described in connection ICO IIO

with the dividing-wheel. This is an entire disk having a cut-awayportion in which the pawl t8 can act and can be moved and adjustedaround its shaft 4 and secured in position by means of a boltt'18 in abracket con the carriage. The spur-wheel i5 gears with a similar wheelce, also loose on a shaft eI just below said wheel yi5 and adapted to bemade fast on its shaft by means of a clutch ef sliding on a key, theother end of this shaft carrying a bevel-gear ec, engaging a similargear cb on the end of a worm ex, that engages the worm -teeth on theedge of the table. Thus it will be seen that the eccentric and rod 'L'move the rock-shaft t4 and by the pawl is move the gear-wheel e0, heldfast by the clutch ef, and through the shaft ed, bevelgears, and wormfeed the carriage toward the tools. When the clutch is open, thecarriage can be adjusted for positioning the work by means of a handleon the squared end of the shaft ed.

The throw-0j mechanism- In the undercut slot e in the table es is anadjustable stop j, having a zero mark or index adjustable along thescale e, and is secured at the desired point to determine the limit offeed of the blank, and consequently the depth of the tooth to be cut.Passing through the carriage there is a rod j, controlled by a spring j,adapt-ed to hit the stopj during the feeding of the carriage, when saidstop moves the rod against the stress of its spring. The opposite end ofthe rod on the other side of the carriage will be correspondingly movedand will allow a spring-held leverj2 to fall through a slotjls.Ordinarily this leverj2 carries in its end a hardened-steel pin j,secured in position by a set-screw prolonged into a handle which restson the squared end of the rod ju; but when the slot registers with thepin j* the leverj2 is pulled down through the slot by a spring jl", thatis hooked to a pin jl in the frame, said lever being arrested in itsmovement by a stop js, projecting from the carriage. This leverj2 ispivoted in a bracket from the carriage at jx and has a shift-yoke jm,that engages the clutch ef, and when the rod is slid through thecarriage by abutting against the stop j the pinjl is pulled through theslot. The lever is pulled down by its spring against the stop j, whichthrows the yokej12 out and disengages the clutch, allowing the wheel eeto run idle. Under the carriage and supported by the bracket elo is abearing e, through which the arcuate rod l0 passes and in which is aclamp-nut @31 to lock them together after the work has been adjusted,thus actuating the arcuate bar and the parallel motion from thecarriage, as described.

The operation is as follows: Supposing we wish to make a bevel-gearhaving one hundred and twenty teeth, we may divide this by adividing-wheel h having two hundred and forty teeth. This dividing-wheelh is clamped on the sleeve g4, and the partial disk hi is clamped bymeans of its set-screw in such a position that the pawl 7L will rideover two teeth and part of the surface L, so that on its return orforward travel it will slide off the surface hi and move thedividing-wheel 7L two teeth. Ve now select a mandrel gl to fit the bossof our wheel-blank W and screw the same home in the head-stock by meansof the screw g8, then place the blank on the mandrel and hold it bymeans of the nut and washer gj and bring the tail-stock (120 forward, sothat the projection from the end of the mandrel is journaled in it. Thecarriage is then moved on its bed and set on the scale in the table tothe angle corresponding to the conicity of the blank. The bolts d8 areloosened and the former-arms set by their scales so that the index-armsc5 are set to the required angle and the bolts d8 tightened. In order toaid this last adjustment, there is a spring-controlled index-finger dkheld in the bracketd2 to which this scale is set. Then theconnecting-rod d is set to the scale on the slotted lever d, alsograduated to read angles of conicity. The former-arms are now clampedrigidly by the bolts through the frame and the wheel is roughed out, andafter this the bolts are loosened and the carriage returned to itsinitial position and clamped to the arcuate rod l0. Power is applied tothe belt-pulley, driving the pinion and spur-gear, which in turn rotatesthe slotted disk and therefrom reciprocates the tools, at the same timerevolving the cam fon the spur-wheel and rocking the lever androck-shaft to vertically reciprocate the bobbin f8, which transmits saidmotion to the rock-shaft h1, which operates the connecting-rod h4, tothe lever to draw the pawl h down, and at the same time cams out thelocking-pawl zL and allows the dividing-wheel 7a, clamped to the sleeveg4, to be tulned the predetermined number of teeth. Every revolution ofthe dividingwheel h, clamped and keyed to the sleeve g4, will cause areciprocation of the eccentric and rod i2 to rock the shaft 4 and movethe pawl is, thus rotating the gears eC and bevel-wheels eC eb to rotatethe worm-gearing with the teeth on the edge of the table to feed thecarriage forward to the cutting-tools.

To produce involute teeth according to this invention, the angle of theradial arm should theoretically be seventy-five and one-half de- -greesto the line joining the former-arm centers, and the length of the radialarm should theoretically vary so as to be one-fourth of the pitch -lineradius. To produce exact work, the distance between the radial-armcenter and the former-arm pivot should be four times the length of theradial arm, or, what amounts to the same thing, the distance between thejoint-line lllC and the formerarm center should be of this length.

It will be observed that in setting up the work in the machine thebevel-wheel blank, which is a frustum of a cone, will be so placed onthe spindle of the carriage that the apex IOO IIO

of the cone will be at the intersection of the line of centers of theformer-arm and spindle, called for the purpose of this explanation thecommon center. The carriage,and of course the blank, is moved toward thecutters, so that an imaginary cutter traveling in the line ofcenters-namely, a horizontal plane-Would traverse an element of the conein this horizontal plane through the axis of the blank` and noadjustment of such a cutter, were it possible to use one, would benecessary for blanks of different taper or cone-angle, for the reasonthatI the positioning of the blank on the spindle of the carriage canalways be made so that such an imaginary cutter will travel along thatelement of the cone lying in a horizontal plane through the axis of thecone. Such an imaginary cutter cannot be used, as I desire to have onecutter travel above and the other below this horizontal axial plane,said plane passing` through the center of the tooth being cut. Now inorder to cut a tooth the cutters are spread apart so that they will cutin planes above and below this horizontal axial plane, converging to thecommon center. The question now arises how much are the tools to bespread. Now referring to the machine, We Will see that each former-arm,which has a length depending on the size of the machine and which Wewill call S, carries at its end an arcuate slot Whose center is thecommon center, and each slot is provided with a graduated scale and anindex-finger. These scales are graduated to read degrees, (these aredegrees and measure the angle of the' tooth, which depends on the numberof teeth in the blank and the pitch,) and the divisions are such thatwhen the former-arms are clamped in position to cut a definite number ofteeth this number Will be cut on a circle Whose radius is V2, whichcorresponds to the base of a cone the slant height of which is S. Nowthis supposes the cutters to be at a distance S from the common center,and as they travel along elements of this cone from base to apex theytravel along the sides of a triangle, and as all lines parallel to thebase of this triangle are proportional the cutters will divide allcircles of which the cone having a slant height S is a locus into thesame number of parts. Thus We get a proper spread of the cutters to cuta miter-Wheel tooth. n

The rotation of the blank to cut successive teeth is accomplished bymechanism on the carriage already fully explained. So far the teeth cutwill be perfect rectangles on their sides, With trapezoidal ends andfaces-in short, they will be pyramidal.

Now we desire to cut instead ot' .ii-at faces such as have a curvedsurface such that a section taken at right angles to the axis .of`

of a tooth consists of two involute curves exi tending from the point ofa tooth to the root; but odontograph teeth, however, are not trueinvolute curves. They are approximations to this, and the practicalshape is usually the arcs of circles struck with a radii of one- .fourththe equivalent spur-Wheel pitch-line radii, whoseceuters are on oppositesides of the tooth on a line making an angle of sevcnty-tive andone-half degrees with the radius and through the pitch-point, thusproducing a tooth the distance between Whose faces is a quantityincreasing from point to root of the tooth. Such a tooth We desire toproduce, and it will be seen that in order to do this the cutters mustbe slightly spread after each cut, and this is done by the lever d,

each of Whose arms is of a length or S tan. 4504-4.

to its chord. This lever d is so linked to the carriage that When saidcarriage moves an angular distance measured by its chord of the arcdescribed with a radius of S inches the lever-arm d Will describe an arcmeasured by a chord of equal length, and the formerarms are spread adistance measured by ordinates dropped from the latter curve to thechord. NOW this vertical motion Will be proportionally reproduced by thetools, and as the amount of movement of the blank toward the tool is thesame as the horizontal movement of the lever d (measured on the chorddescribed by it as an abscissa) the curve cut by the tools Will be areproduction of that described by the lever d-that is, an arc Whoseradius is one-fourth the pitch-line radius. Thus far ruiter-gears havebeen taken as the type of Wheel cut, but the machine is not limi-ted tocutting these only.

As described above, the radial arm d has a length of X S tang. ofcone-angle,

and if gears having a greater cone-angle than forty-ive degrees are tobe cut it will be noticed that in this formula the tangent of the angleis an increasin Jr uantit 1 for all Wheels D D IOO IIO

cnlty and still maintain the given length of the Y radial arm a methodof adjustment had to be devised to meet the requirements, so that thecurve cut by the tool would still have a radius of one-fourth thepitch-line radius of the equivalent spur wheel. This adjustment must besuch as to produce a movement of the lever-arm slower than that of theblank, for the length of this arm would be The versed sine of this arcwill be, Say, H. Next nd that arc that has the same versed sine H and aradius tan. 4

and find the length of its chord N. The ratio oi' these chordsmultiplied by the selected distance L on the slotted lever dc will givethe new length the fixed radius that will determine the motion of theradial arm d, so that the tool will cut a flatter curve than onmiter-gears. The same formula applies to gears having a cone-angle lessthan forty-five degrees; but here the movement of the radial arm must befaster than the carriage, so as to produce a greater curvature. The newdistance L" will be longer than the others. Now in making this lastadjustment the radial arm d is thrown out of position-t'. c., does notmake seventy-five and one-half degrees with the horizontal, so that anadjustment for this deviation is necessary, which is made by the scale(Z7, in which graduations measure the distance D of the end of theradial arm from a vertical and is found by the following:

equals one-half the chord of that arc which has a versine of ll and aradius of S tan. of cone-angle #MF sine 147570.

or the corrected position of the radial arm of the machine is D= B CThese last two scales read cone-angles, so that the workman will have nocalculating to do, and makes adjustments to but twoquantities-cone-angle and number of teeth.

In the place of the springpoint index shown for adjusting theparallel-motion I may use a beveled plate secured to the top of theupper channel d20, which can be set to a vertical line on the face ofthe standard cl2, in which case the overhanging arm of said standardwill be cut off.

The machine will cut in volute teeth. The arrangement of theparallel-motion, formerarms, and radial arms with the carriage give theshape to miter and bevel wheels without the use of templets or Shaperson the principle of the odontograph.

Having thus described my invention, what I claim as new therein, anddesire to secure by Letters Patent, is-

l. In agear-cutting machine, a parallel-motion, a former-arm connectedto a member thereof, a tool reciprocablc on the formerarm, awork-carriage organized to feed work to the tool and proportionatelymove the former-arm, substantially as set forth.

2. In a gear-cutting machine, the combination with a pivoted former-arm,of a tool reciprocable thereon, means for adjusting the inclination ofsaid arm to cnt gears of diiferent conicity, a parallel-motion, awork-carriage adapted to feed the work to the tool, and mechanismconnecting the work-carriage and parallel-motion, whereby the former-armis moved to cause the tool to cut a curved tooth-face, substantially asset forth.

3. In a gear-cutting machine, the combination with a pair of former-armshinged on a common fulcrum,reciprocating tools thereon, acentrally-pivoted radial arm each end of which is connected byintermediate devices to a former-arm adapted to change the spread of theformer-arms, a work-carriage movable about a pivot and mechanismoperated by IOO IZO

the carriage to change the angnlarity of said radial arm, substantiallyas set forth.

4:. In a gear-cutting machine, a parallel-motion, a pair of former-armssupported by links from the horizontal members thereof, a toolreciprocable on each former-arm, a Work-carriage organized to feed thework to the tools, and mechanism operated by the work-carriage to causea variation in the spread of the parallel-motion, and former-arms,substantially as set forth.

5. In a gear-cutting machine, a pair of lever-ar ms pivoted at one end,slotted free ends thereon, a parallel-motion each of the horizontalmembers thereof connected to one of said slotted free ends, and a leveroperated from the Work-carriage and operating the pa rallel-motion, allin the proportions set forth.

6. In a gear-cutting machine, the combination with a pair of former-armspivoted at one end, a parallel-motion adjustably connected to theirother ends, a working carriage, a rod adapted to be clamped to saidcarriage, said rod and an intermediate mechanism adapted to vary thespread of the parallel-motion, substantially as set forth.

7. In a gearcutting machine, a pair of former-arms having a commonfulcrum, tools reciprocating on said arms, a parallel-motion, the freeends of said lever-arms connected thereto, a work-carriage adapted tofeed work to the tools, and mechanism operated by the carriage to varythe parallel-[notion and thereby the spread of the lever-arms,substantially as set forth.

8. In a gear-cutting machine, a pair of former-arms having a commonfulcrum at one end and enlarged slotted free ends, a parallelmotion,means for adjustably connecting the parallel-motion and free ends of theformerarms to cut wheels of different conicity, a carriage adapted tofeed work to the tools, and mechanism between the carriage andparallelmotion to vary the spread of the lever-arms, substantially asdescribed.

9. In a gear-cutting machine, mechanism for varying the spread of thetools comprising a pair of parallel channels connected by links of equallength and inclination, a rod connecting one of said links with aslotted lever, in combination with a work-carriage and mechanismconnected thereto to operate the said slotted lever, substantially asset forth.

10. In a gear-cutting machine, a pair of lever-arms having a commonfulcrum at one end, in combination with a parallel-motion comprising twoparallel channels, sliding blocks in each channel, the free ends of saidlever-arms connected to said blocks, a Workcarriage, and means connectedto the workcarriage to vary the spread of the lever-arms, substantiallyas described.

11. In a gear-cutting machine, a parallelmotion, apair of former-armslink-supported from the horizontal members thereof, means for adjustingthe spread of the former-arms,

a tool reciprocable on each arm, a carriage arranged to feed Work to thetools and mechanism operated by the carriage to vary the spread of theparallel-motion and former-arms, substantially as set forth.

12. In a gear-cutting machine, a throw-off mechanism on the carriage,comprising a pusher-bar, a slot in one end thereof, a springheld leverresting on said bar and adapted to pass th rough the slot in the bar,feed-gear and a clutch operated by the spring-held lever to disengagethe gear from its shaft, substantially as set forth.

13. In agear-cutting machine, atool-holder comprising a base, atool-carrier hinged thereto, aspring adapted to hold the same in normalposition, means for universally adjusting the tool, and a cam adapted tocam the toolcarrier and tool away from the face of the Work,substantially as described.

14. In a gear-cutting machine, a parallel- -motion, a pair offormer-arms connected to the horizont-al members thereof, means foradjusting the spread of the former-arms, independent means for adjustingthe spread of the horizontal members of the parallel-motion, aWork-carriage, an arcuate rod adjustably connected thereto, andmechanism operated by said rod and organized to Vary the spread of theparallel-motion and formerarms, substantially as set forth.

15. In a gear-cutting machine, the combination with a carriage feedingWork to the tools; of mechanism for varying the spread of the tools,comprising a parallel-motion, means for adjusting the inclination of thelinks of said parallel-motion, a lever, an arcuate rod adjustablyconnected to said carriage and arranged to impart motion to said lever,and a rod between said lever'and parallelmotion and adjustable in theformer, substantially as set forth.

16. In a gear-cutting machine, former-arms having motion around a pivot,tool-holders thereon and mechanism for reciprocating said tool-holders,in combination with a parallelmotion for varying the spread of saidformerarms, and devices for moving the tools from the face of the workduring their return travel, substantially as set forth.

17. In a gear-cutting machine, the combination With a pair of pivotedformer-arms and enlarged slotted ends on said arms, of a parallel motioncomprising parallel channelshaped members and links organized tosimultaneously move said members parallel to each other, blocks slidablein said channels, parts pivoted in said blocks and adjustably secured tothe slotted ends of said former-arms, substantially as set forth.

18. In a gear-cutting machine, the combinat-ion with a pair of pivotedformer-arms and enlarged slotted ends on said arms, of a parallel-motioncomprising parallel members and links organized to simultaneously movesaid members, blocks slidable in relation to IOO IOS

IIO

said parallel members and connected to said former-arms, and mechanismorganized t0 vary the spread of said parallel-motion, substantially asset forth.

19. In a gear-cutting maehine, the Combination with a pairof pivotedformer-arms, and a parallel-motion connected to the formerarms, of aWork-carriage revoluble 0n a pivot, a rod adjnstably secured to saidcarriage, a swinging lever operated by said rod, and a link eonneetingthe parallel-motion to said lever and adjustable therein, substantiallyas sel, forth.

20. In a gear-cutting machine, the combination with former-arms havingTa Common pivot, tools reeiproeable on each, of a parallelniotion, meansfor setting the spread of 'the former-arms to eut different gears, meansfor adjusting on the parallel-motion the spread ofthe former-arms, andindependent means for regulating the movement of the parallelmotion,Substantially as set forth.

21. In a gear-cutting machine, a throw-0n? mechanism on the carriageComprising Coperating gear-wheels organized to move said carriage, aspring-held pusher-bm', a springheld bell-crank lever organized t0 moveone of the gear-Wheels into and out of operative relation with itsCooperating wheel, said lever arranged to be released hy said pusherbarat the end of the travel of said carriage to canse a gear to run idle,substantially as set forth.

In testimony that I claim the foregoing as my invention I have signed mynaine in presence of two subscribing witnesses.

THEODORE COVEN'IRY.

Vitnesses:

PETER J. LIVSEY, WILLIAM FAULKNER.

